DART, an
$110 million experimental space mission designed to test automated docking
technology, ended prematurely late Friday after its launch from Vandenberg Air
Force Base in California, NASA said today.
NASA's DART (Demonstration of Automated Rendezvous Technology) was launched
Friday at 1:25 p.m. EDT from a Pegasus rocket, which was released from a
Stargazer L-1011 aircraft at 40,000 feet over the Pacific
Ocean.
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Click here for a blow-by-blow account of DART's launch and 24-hour mission.
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The first sign of anything unusual was during on-orbit checkouts, when ground
controllers saw higher than anticipated navigation errors, project manager Jim Snoddy said today.
During the subsequent rendezvous phase, "everything was working wonderful," he
said. "We had high accuracy."
In orbit, DART was to fly around the Earth and rendezvous with an experimental
communications satellite launched in 1999. It was to get about 16 feet from the
satellite and perform several up-close maneuvers using a guidance sensor aboard
DART and Global Positioning System satellite navigation information.
The 800-pound DART successfully met up with its target satellite and approached
within about 300 feet, but managers noticed it was using fuel too fast.
The guidance system sensed the empty fuel tank and commanded the spacecraft to
retreat and enter the safe orbit that should lead it to burn up in the
atmosphere within 10 years, Snoddy said.
DART was executing an engine burn that would put it in that orbit today.
Snoddy wouldn't speculate why the craft lost fuel so
quickly -- it started with enough to do all its maneuvers twice, plus a 30
percent margin -- but said managers had not seen evidence of a leak.
NASA is forming a mishap investigation board to look into the failure.
Snoddy said some of DART's
technology was proven in the aborted mission, but not the critical maneuvers
that would demonstrate the ability of a spacecraft to dock without human
intervention.
"We've done what nobody's ever tried to do before," Snoddy
said of DART, which was "high risk" in that, to save money, it had limited
ability to communicate or fix problems on the fly during its planned 24-hour
mission.
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